A conventional system that remotely controls an in-vehicle device conducts bidirectional communication between a vehicle-side device and a mobile device to determine whether the mobile device is an authorized (regular) mobile device carried by a user. For example, this system is disclosed in JP 2000-104429A. This type of remote control system is known as a smart key system, which has a transmitter as the vehicle-side device and conducts a bidirectional communication between the transmitter and the mobile device. As the transmitter, there are normally provided plural transmitters having detection areas different from each other. For example, three transmitters are so disposed as to define the detection areas in a given range outside a right door, a given range outside a left door, and a given range outside a trunk door, respectively. If additional detection areas at the left and right sides of the vehicle are defined as front and rear areas, five transmitters are provided.
Transmission request signals are transmitted to the detection areas from the plural transmitters, respectively. When a mobile device exists within the detection areas in which the transmission request signals are transmitted and received, the transmission request signal is received by the mobile device, and the mobile device transmits a given response signal responsive to the received transmission request signal. The response signal is received by a receiver equipped in the vehicle, and a given matching process is conducted on the response signal by a vehicle-side device. Then, when matching can be made, it is determined that the mobile device that has transmitted the response signal is an authorized mobile device. As a result, an operating state of the in-vehicle device such as a door lock mechanism is controlled based on the determination result.
In the conventional remote control system, it is sometimes difficult that the user recognizes whether the control of the in-vehicle has been conducted based on the determination as a result of the matching, even if it is determined that the device is the authorized mobile device. Under this circumstance, in the remote control system where an in-vehicle device to be controlled is a door lock mechanism, when the door is locked based on the determination that the mobile device that has approached the vehicle and entered the detection area is an authorized mobile device, it is proposed that a compartment lamp is lighted to notify that the door is unlocked, or foot lamps disposed on side mirrors for illuminating the foot areas of front seat doors are lighted to notify that the door is unlocked.
In either of those cases, the same notification operation is executed without distinguishing in the detection area of which transmitter the mobile device exists. However, it is difficult that the user recognizes the fact that the compartment lamp is lighted without closely approaching the vehicle, except for night. Also, even if the foot lamps that are disposed on the side mirrors are lighted, it is difficult to recognize this fact unless the user is present at a position relatively close to the front seat door. For this reason, for example, when the user carrying the mobile device approaches the vehicle toward the rear seat doors, it is not always easy to recognize that the mobile device is determined as the authorized mobile device, and the door is unlocked. Thus, the conventional remote control system is not sufficiently satisfactory to users.